The present invention relates to a drive mechanism for an image transfer type copying apparatus, and more particularly to a drive mechanism suitable for high speed copying with accuracy in synchronism maintained.
As a drive system for an image transfer type copying apparatus, it has been a general practice to employ a single drive source to drive all the elements necessary for copying such as an original scanning means, a photosensitive member, a developing means and a feeding means for copying paper. In order to achieve high speed copying in this type of copying apparatus, it is generally necessary to increase scanning and return speeds of the original scanning means and in particular requires the speed of return movement to be increased. However, the problem may arise in this case that if a shock or an impact at the change of the scanning means from the scanning movement to the return movement is large, variance in moving speed of the photosensitive member will be caused which in turn causes the slippage of image transfer onto copying paper resulting in poor transfer of image. Additionally, there is a necessity to provide relatively large sized developing means in order to increase capacity for developer in high speed copying and this will inevitably increase the drive torque of the developing means. As a result, sudden changes in loads will occur at the times of energization and deenergization of drive for the developing means which in turn causes changes in speeds of the scanning means, photosensitive member, feeding means and other elements so that the final copy obtained will have an image with slippages in synchronism and image transfer. Accordingly, the slippages in synchronism as well as in image transfer caused by return movement of the original scanning means, or by energization and deenergization of the developing means will influence the copying operation either directly or indirectly through the drive source by large changes in loads so that these defects or disadvantages were basically unavoidable in the conventional high speed copying apparatus with a single drive source to drive all the elements.